1. Field of the Invention
The present invention pertains to a support system for a gas delivery mask, and, in particular to a forehead support system for a gas delivery mask and to a system for supplying a flow of gas to a patient that incorporates such a forehead support system.
2. Description of the Related Art
There are numerous situations where it is necessary or desirable to deliver a flow of breathing gas non-invasively to the airway of a patient, i.e., without intubating the patient or surgically inserting a tracheal tube in their esophagus. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation. It is also known to deliver continuous positive airway pressure (CPAP) or variable airway pressure, which varies with the patient's respiratory cycle, to treat a medical disorder, such as sleep apnea syndrome, in particular, obstructive sleep apnea (OSA), or congestive heart failure. Non-invasive ventilation and pressure support therapies involve the placement of a patient interface device, which is typically a nasal or nasal/oral mask, on the face of a patient to interface the ventilator or pressure support device with the airway of the patient so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient. It is known to maintain such masks on the face of a patient by a headgear having upper and lower straps, each having opposite ends threaded through connecting elements provided on the opposite sides and top of a mask.
Because such masks are typically worn for an extended period of time, it is important the headgear maintain the mask in a tight enough seal against a patient's face without discomfort. A problem arises in that in order for the mask to maintain a seal without any undue gas leaks around the periphery of the mask, the mask may be compressed against the patient's face.
It is known to provide forehead supports associated with gas delivery masks to provide a support mechanism between the mask and the patient's forehead. Gas delivery masks having forehead cushions, spacers or supports are described in U.S. Pat. Nos. 4,907,584; 5,243,971; 5,517,986; 5,570,689; 6,119,693 and 6,357,441. The forehead supports prevent the mask from exerting too much force on a patient's face at one general location by dispersing the load over a larger area, provides greater control of the force on the patient at certain pressure points, such as at the bridge of the nose, and provides stability to the mask.
Another mask with forehead support is disclosed in International Publication No. WO 00/78384 A1. In this arrangement a forehead support is adapted to be secured to a respiratory mask. The forehead support includes a joining member for securing to the mask and a cushion frame pivotally mounted to the joining member. While pivotal movement of the cushion frame to the joining member in one dimension allows the position of the forehead cushions to be adjusted, it does not optimize the ranges of positions for the forehead on a human head.
From the above-identified conventional masks, it can be appreciated that an advantage exists for increased stability of the gas delivery mask support. Another advantage exists for a forehead support that evenly distributes headgear strapping force. A further advantage exists for a mask that has an adjustable forehead support adaptable to a wide range of forehead configurations and sizes. Still yet, a further advantage exists for a forehead support bracket that allows the headgear and mask to be donned separately.